I have mixed feelings about Trainz. I have spent many hours happily playing this game, but it comes with a healthy dose of disappointment which makes it hard to recommend at full retail value.
The real disappointments for me were:
* Not only framerate, but application responsiveness takes a massive hit without severely limiting texture qualities and draw distance, making for a high cost to actually take advantage of the game's nice graphics. I understand 3D worlds require resources, but I had a relatively new nvidia GPU and was getting pretty disappointing performance even with a bit of graphics options tuning to reduce quality for the sake of performance.
* Included sessions (for which there are steam achievements) are often glitchy or tempermental in their willingness to aknowledge your progress. For example, a signal which should turn green when you complete your train does not, and you are stuck 1-2 hours into a scenario, unable to complete it because running the red light would count as a rule violation and prevent successful completion of the session. Or you are told that you will be carrying a train to the destination, complete with messages throughout about how your train needs to use specific tracks due to its length, but you actually have is a locomotive, with no train. Which you can actually complete the session with, though it seems silly.
* The developer, n3v/auran, has now embarked on a kickstarter campaign to fund creation of "Trainz: A New Era" which pretty effectively kills my hope of the graphics performance ever being improved or the session bugs ever being corrected.
That all said, however, I have enjoyed this game quite a bit since I got it. The driving experience lets you choose often (in some sessions you are forced to use one or the other) whether to use DCC or CAB mode. DCC seems to emulate an electric model railroad with a simple knob to control movement. CAB mode attempts to emulate real railroads (I am not qualified to say how close it comes) by making the user interact with the reverser (forward/reverse/neutral), a range of throttle notches from -9 to 9, and, for when the engine is pulling cars and the e-brake won't cut it, a complex train brake where you cycle through initial -> lap -> application and watch the various brake pipe/cyl pressures adjust as they eventually bring the train to a stop. The graphics can be nice, and seems many in-game objects have detailed dynamic behavior, from trees which have different graphics for each season, to train cars which have specific loading/unloading animations. The content update hub is also a place for users to post their own content, and for other players to add it to their own collection, not unlike the steam workshop. One can download locomotives, stock, scenery, routes, sessions, etc. which the community has uploaded simply by searching the interface and choosing to download it. The system addresses revisions by content publishers in the community so that new revisions are included when other players with their content perform normal content updates.
The game has a surveyor mode, where you can create your own train routes and sessions, laying out terrain, tracks, signals, scenery, triggers, session start/end points, etc.. I played with it a little, covering the wireframe ground with white (I called it snow) and a loop of track that had a switch off to a roundhouse, where some engines which the community published were sitting. I got bored before it got close to anything I'd hoped it might become, but perhaps more patient or creative people might enjoy that feature more. It's certainly a nice feature to be able to build your own entire world/route, session rules/plot, etc, and then turn around and play the session in driver mode to enjoy the fruits of your creativity. Being able to publish the results to the community if you are happy with your work is also a great feature.
I had tried TS2014 in the hopes of finding a less buggy way to scratch the train sim itch, but was far less pleased with the control options and found myself craving Trainz CAB mode over TS2014 controls.
All in all, I think this game is a great sandbox, with some crazy requirements for full graphics performance, and a handful of glitchy/buggy sessions. While the community may continue to contribute content to the game, seemingly keeping it alive, the engine is dated and not looking like it will ever be updated. For the retail price, there are almost certainly more actively developed train simulator solutions. If you already own it though, you may get many hours of fun out of it.